DEVELOPMENT AND EVALUATION OF AN INDIRECT ELISA TO DETECT ANTIBODIES TO ABORTION STRAINS OF CHLAMYDIA-PSITTACI IN SHEEP SERA

A novel indirect enzyme-linked immunosorbant assay (ELISA) for antibod ies against abortion strains of Chlamydia psittaci (C. psittaci) has b een developed. The antigen used was chlamydial elementary bodies treat ed sequentially with N-lauroyl sarcosine and n-octyl-beta-D-glucopyran oside and finally solubilized with N-lauroyl sarcosine and dithiothrei tol. Treating the antigen with sodium periodate after coating of the p lates increased the specificity for antibodies to abortion strains. Th e test was evaluated initially with sera from experimentally infected sheep and an uninfected control group. These sheep were monitored for lambing performance and infection status. When used in conjunction wit h the indirect micro-immunofluorescence test (MIF), the ELISA was able to identify as negative all twenty-five sera from ewes that had no ty pical placental lesions and identified as positive twenty of twenty-on e sera from infected ewes that had either typical placental lesions or had been found positive by isolation of chlamydia in cell culture. Th e combination of ELISA and MIF was also able to discriminate correctly groups of sera from six flocks with a history of infection from four known uninfected flocks.